Needle roller bearing

Abstract

The object is to efficiently subject steel retainers of needle roller bearings to heat treatment in a short period of time even in small-lot production using compact treatment facilities, thereby producing retainers having improved resistance to wear and surface damage and high in fatigue strength and fracture strength as a whole. The steel retainer 3 , which retains needle rollers 2 , is formed from a steel plate containing 0.15 to 1.10% by mass of carbon. After forming, the steel plate is subjected to induction heat treatment comprising induction hardening and induction tempering. Such heat treatment can be carried out efficiently in a short period of time, using compact treatment facilities, even in small-lot production. The retainer 3 thus formed is sufficiently resistant to wear and surface damage, and is high in fatigue strength and fracture strength as a whole.

1 . A needle roller bearing comprising a plurality of needle rollers and a steel retainer retaining said needle rollers, characterized in that said steel retainer is subjected to induction heat treatment comprising at least induction hardening over the entire area and entire thickness thereof.  
     
     
         2 . The needle roller bearing of  claim 1  wherein said induction heat treatment further comprises induction tempering.  
     
     
         3 . The needle roller bearing of  claim 1  further comprising at least one bearing ring selected from inner and outer rings.  
     
     
         4 . The needle roller bearing of  claim 1  wherein said steel retainer has a surface hardness and an inner hardness within a range of 350 to 700 HV in terms of Vickers hardness.  
     
     
         5 . The needle roller bearing of  claim 1  wherein the carbon content of said steel retainer is within a range of 0.15 to 1.10% by mass.  
     
     
         6 . The needle roller bearing of  claim 2  further comprising at least one bearing ring selected from inner and outer rings.  
     
     
         7 . The needle roller bearing of  claim 2  wherein said steel retainer has a surface hardness and an inner hardness within a range of 350 to 700 HV in terms of Vickers hardness.  
     
     
         8 . The needle roller bearing of  claim 3  wherein said steel retainer has a surface hardness and an inner hardness within a range of 350 to 700 HV in terms of Vickers hardness.  
     
     
         9 . The needle roller bearing of  claim 2  wherein the carbon content of said steel retainer is within a range of 0.15 to 1.10% by mass.  
     
     
         10 . The needle roller bearing of  claim 3  wherein the carbon content of said steel retainer is within a range of 0.15 to 1.10% by mass.  
     
     
         11 . The needle roller bearing of  claim 4  wherein the carbon content of said steel retainer is within a range of 0.15 to 1.10% by mass.